PHP Socket Server vs node.js: Web Chat

Question

I want to program a HTTP WebChat using long-held HTTP requests (Comet), ajax and websockets (depending on the browser used). Userdatabase is in mysql. Chat is written in PHP exc

Answer 1

Another topic which I answered which could help you and will easily scale to your needs => How to use redis PUBLISH/SUBSCRIBE with nodejs to notify clients when data values change?

Answer 2

JavaScript, or in this case V8 which is the engine that Node is using, is by design single threaded. So yes there's just an event queue.

But in the end, that's not a problem, something's always gonna happen first, unless you're using multiple processors, and even then, you will most likely only have one network card... one router... you get the idea. Also, using 1000+ threads... not a good idea, scales badly, and you will find yourself in a concurrency HELL.

1000 chat users, that will be no problem at all for Node.js.

I can give you a pretty basic idea how you would set it up, this plain vanilla chat thingy works over telnet, it has.. no features, but it works:

var net = require('net'); // require the net module

var users = []; // keep track of the users

// setup a new tcp socket server
net.createServer(function(socket) { // provide a callback in case a new connection gets
                                    // established, socket is the socket object

    // keep track of this users names, via use of closures
    var name = '';

    // ask the new user for a name
    socket.write('Enter a Name(max 12 chars): ');

    // register a callback on the socket for the case of incoming data
    socket.on('data', function(buffer) { // buffer is a Buffer object containing the data
        if (name !== '') {  // in case this user has a name...

            // send out his message to all the other users...
            for(var i = 0; i < users.length; i++) {
                if (users[i] !== socket) { // ...but himself
                    users[i].write(name + ': '
                                   + buffer.toString('ascii').trim()
                                   + '\r\n');
                }
            }

        // otherwise take the data and use that as a name
        } else {
            name = buffer.toString('ascii').substring(0, 12).trim().replace(/\s/g, '_');
            socket.write('> You have joined as ' + name + '\r\n');

            // push this socket to the user list
            users.push(socket);
            for(var i = 0; i < users.length; i++) {
                if (users[i] !== socket) {
                    users[i].write('> ' + name + ' has joined' + '\r\n');
                }
            }
        }
    });

    // another callback for removing the user aka socket from the list
    socket.on('end', function() {
        users.splice(users.indexOf(socket), 1);
    });

// bind the server to port 8000
}).listen(8000);

There's no magic involved in here (besides the use of a closures), you don't have to do with raw socket programming and you won't have any concurrency problems. And you learn some of the latest hotness ;)

I recommend that you watch some of the talks that are listed on our Node.js tag wiki, to get a better grasp of how Node.js works.